"The fewer the ingredients, the less likely to cause contact dermatitis."

Research shows that key ingredients in sodas cause etching of the teeth.

Meals that include complex ingredients cause additional strain on a person's health, simple food is to be preferred.

Some ingredients of sunscreens can cause the skin to become more sensitive.

The ingredients can cause bad reactions in some children.

And a particular ingredient that bothers someone after one meal may cause no problems at all after another.

"The evidence is not convincing that these ingredients cause weight loss," he said.

An ingredient in some cinnamon products, coumarin, may cause liver problems.

Scientists do not know why the ingredient might cause a stroke, although they said its effect on blood pressure might play a role.

But even the ingredients they do use can cause problems.